I. Field
The present disclosure relates generally to communication, and more specifically to techniques for operating a user equipment (UE) in a wireless communication system.
II. Background
Wireless communication systems are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless systems may be multiple-access systems capable of supporting multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal FDMA (OFDMA) systems, and Single-Carrier FDMA (SC-FDMA) systems.
A UE (e.g., a cellular phone) in a CDMA system may employ a rake receiver to process a received signal. The rake receiver may include a searcher and multiple demodulation elements (or rake fingers). The searcher may search for strong multipaths in the received signal. The rake fingers may be assigned to process strong multipaths found by the searcher. Each rake finger may process its assigned multipath and provide detected symbols for that multipath. The detected symbols from all assigned fingers may then be combined to obtain data symbol estimates. The rake receiver can provide acceptable performance for a CDMA system operating at low geometry, e.g., low signal-to-interference-and-noise ratio (SINR).
An equalizer may also be used to process the received signal. The equalizer may attempt to reduce all noise components such as thermal noise, interference due to other transmissions, and inter-symbol interference (ISI) that can come from multipath and distortion in the wireless channel. At high geometry, ISI may become dominant. The equalizer may be able to more effectively combat ISI than the rake receiver. Hence, the equalizer may be able to provide better performance than the rake receiver at high geometry.
The UE may employ a diversity receiver with multiple receive antennas to obtain diversity against deleterious path effects. At least one propagation path typically exists between a base station antenna and each of the receive antennas at the UE. If the propagation paths for different receive antennas are independent, which is generally true to at least an extent, then diversity increases and the received signal quality improves when multiple antennas are used to receive the signal from the base station.
The UE may have various hardware blocks to process a transmission received via one or more antennas. These hardware blocks consume power when operational. It is desirable to reduce power consumption by these hardware blocks in order to extend battery life for the UE.